Chronic obstructive pulmonary disease (COPD) is a respiratory condition that often reduces the ability of one or both lungs to expel air completely during the exhalation phase of the breathing cycle. Such disease is accompanied by chronic or recurrent obstruction to air flow within the lung. COPD may be accompanied with complications such as chronic bronchitis, bronchiectasis, asthma, and/or emphysema. Problems may intensify when patients have overlapping characteristics including two or more such complications, for example, emphysema and chronic bronchitis.
Emphysema is a condition of the lung characterized by the abnormal permanent enlargement of the air sacs located distal to the terminal bronchiole, accompanied by the destruction of their walls, and without obvious fibrosis. It is known that emphysema and other pulmonary diseases reduce the ability of one or both lungs to fully expel air during the exhalation phase of the breathing cycle. One of the effects of such diseases is that the diseased lung tissue is less elastic than healthy lung tissue, which is one factor that prevents full exhalation of air. During breathing, the diseased portion of the lung does not fully recoil due to the diseased (e.g., emphysematic) lung tissue being less elastic than healthy tissue. Consequently, the diseased lung tissue exerts a relatively low driving force, which results in the diseased lung expelling less air volume than a healthy lung. As a result, air remains trapped in the diseased portions of the lung.
Conventional treatment methods for emphysema include Lung Volume Reduction Surgery (LVRS), which includes surgical removal of the diseased portion of the lung. Recent advances also include devices that isolate a diseased region of the lung in order to reduce the volume of the diseased region, such as by collapsing the diseased lung region. However, such devices are still in the development stages. Thus, there is much need for devices and methods for regulating the flow of air into and out of diseased portions of a patient's lungs.